.diyi {
    width: 250px;
    height: 500px;
    border: 1px solid;
    border-style: outset;
}

li {
    list-style-type:none;
    height: 25px;
    line-height: 25px;
}
a {
    text-decoration:none;
    color: black;
}
a:hover {
    color:silver;
    transition: all 0.3s ease-in-out;
}
            